Transversal grain size effect on the phase-transition hysteresis width of vanadium dioxide films comprising spheroidal nanoparticles

Grain size of vanadium dioxide (VO2) films or isolated particles is known to play an important role in the modulation of temperature dependence of the hysteresis width in semiconductor to metal transition. In order to investigate the effect of grain size on the hysteresis width, we prepare a range of VO2 films consisting of spheroidal nanoparticles whose mean size was hugely modulated from 49.4 to 77 nm by an annealing time increasing from 15 to 90 min. However, regardless of the annealing time, the films show similar crystal structure and morphology. More interestingly, experimental results show that the hysteresis width is inversely proportional to the average transversal grain size of VO2 films. We offer quantitative explanations for the observed grain size dependence of the hysteresis width. This work will provide a more precise picture of the role of the grain size on the hysteresis width of VO2 films.